1. Field of the Invention
This invention relates to heating devices and more particularly to an immersible water heater.
2. Prior Art
The provision of means to insure that non-protected small bodies of standing water do not freeze in colder climates constitutes a recognized problem. One specific example of such small water bodies includes the group of animal feeding devices. Where animals are kept outdoors or in unheated enclosures, it is necessary that they be provided with drinking water. It is also therefore necessary to insure that the drinking water will not freeze.
This problem is most prominent in small quantity feeding sources, such as for example, water buckets. Where such buckets, small troughs, and the like are provided, it is extremely important that the means provided to prevent freezing to be relatively inexpensive and foolproof. Although immersion type heaters have been known for a long time, and are readily available at satisfactory prices, they have two major drawbacks. First, when immersed in the water, the coil becomes quite hot and can damage the animal's tongue. Protection must be provided against this occurring. Secondly, unless some automatic shutoff device is provided, such immersion coils can overheat the water and, in the absence of water, either due to tilting of the bucket or exhaustion of the water through evaporation or drinking, the coil can do significant damage to the bucket, including to metal buckets or troughs and surrounding areas.
Although it has been known to use thermostats in connection with immersion heaters, where the thermostat is designed to sense the temperature of the immersion heater, shutoff can occur at a point where the upper reaches of a body of water can still freeze. Attempting to overcome this by allowing a higher setting of the thermostat can result in damage to the bucket and in overheating of small bodies of water. Thermostats which attempt to sense the temperature of the water have a distinct disadvantage in that they will not turn off the immersion heater when the bucket is empty and the atmosphere is colder than the shutoff point. This again can lead to damage of the bucket.
It would therefore be an advance in the art to provide an inexpensive immersion type water heater which overcomes the disadvantages enumerated above.